1. Field of the Invention
The invention relates to an electrical fan. More particularly, the invention relates to an electrical fan in which lubricant oil loss is prevented. Thereby, evaporation of the oil retained in the fan can be greatly reduced, and the longevity of the fan can be substantially increased.
2. Description of the Related Art
One type of conventional fans is shown in FIG. 1 and FIG. 2. In FIG. 1 and FIG. 2, the conventional fan mainly consists of a blade module 1, a coil module 2, a circuit board 3, and a base substrate 4. A space 11 is usually defined in the blade module 1 for accommodating the coil module 2. A shaft 12 is mounted at a center of the space 11, and further penetrates through the coil module 2 being placed into the space 11. The shaft 12 and the blade module 1 are together driven in rotation by means of the polarization change of the coil module 2. The coil module 2 has a case 21 which size matches the space 11. A magnet 22, a frame 23 around which coils 24 are wound, a copper-made shaft sleeve 25, an oil-retaining bearing 26, and a buckle 27 are assembled with one another into the case 21. The frame 23 and the coils 24 are mounted inside the magnet 22. The shaft sleeve 25 is mounted inside the frame 23. The oil-retaining bearing 26 is mounted inside the shaft sleeve 25. The buckle 27 which have, for example, a C-shape, abuts against a bottom of the oil-retaining bearing 26 to enable the oil-retaining bearing 26 to engage with a groove 121 defined at a lower end portion of the shaft 12. The shaft sleeve 25 is attached to the circuit board 3 and the base substrate 4.
The oil-retaining bearing 26 contains oil for lubricating the shaft 12 and the coil module 2 when the fan rotates, especially at high speed. Rotating the fan at high speed generates a lot of heat, and allows the oil contained in the oil-retaining bearing 26 to flow upward. The oil-retaining bearing 26 has an opened top through which the lubricant oil flows from the oil-retaining bearing 26 and evaporates. Once the lubricant oil is completely consumed, the rotating fan is no longer provided with lubricant oil. A substantial amount of heat is thus increasingly generated by friction, resulting in noise or malfunction.
Another type of conventional fans is illustrated in FIG. 3. In FIG. 3, the lubricant oil of the oil-retaining bearing 26 evaporates at reduced speed by means of plastic gaskets 281, 282 mounted on a top and a bottom of the oil-retaining bearing 26, respectively. The plastic gasket 281 absorbs most of the upward oil flowing. The plastic gasket 282 absorbs the remaining lubricant oil flowing downward once the fan has stopped. Thereby, the lubricant oil of the oil-retaining bearing 26 is prevented from leaking out. The main function of the oil-retaining bearing 26 is to contain the lubricant oil flowing through the bearing to provide lubrication. However, the plastic gasket 281 progressively absorbs the lubricant oil flowing upward and the plastic gasket 282 progressively absorbs that flowing downward. The lubricant oil in the oil-retaining bearing 26 is thus increasingly reduced. Moreover, the lubricant oil absorbed by the plastic gaskets 281, 282 may evaporate through an externally exposed area of the plastic gaskets 281, 282.
Therefore, an improved fan that has a longer longevity without lubricant oil loss is needed.
It is therefore a principal object of the invention to provide an improved fan in which a stopper ring is mounted around a top of an oil-retaining bearing to buckle the oil-bearing bearing and stop a lubricant oil from leaking out. Thereby, evaporation or leakage of the oil retained in the fan can be favorably reduced, and the longevity of the fan can be substantially increased.
It is another object of the invention to provide an improved fan, in which a bottom of the shaft sleeve is provided with a wear resistant sheet, and optionally further provided with a magnet, and a magnetically susceptible sheet in order to prevent the oil contained in the oil-retaining bearing from leaking out.
In accordance with the above and other objectives, the invention provides an improved fan that comprises a blade module and a coil module. The blade module includes a shaft and a recess. The recess defined in the blade module has a bottom where an end portion of the shaft is embedded. The coil module includes an oil-retaining bearing, an oil stopper ring and a shaft sleeve. The shaft sleeve has an internal flange at a top thereof. The oil-retaining bearing is mounted inside the shaft sleeve, and the oil-retaining ring is clamped between the internal flange and the oil-retaining bearing after the shaft of the blade module penetrates through the shaft sleeve and the oil-retaining ring. Via the oil stopper ring, the oil is retained in the oil-retaining bearing without substantial loss and evaporation. Thereby, the longevity of the fan of the invention is greatly increased.
To provide a further understanding of the invention, the following detailed description illustrates embodiments and examples of the invention, this detailed description being provided only for illustration of the invention.